This invention relates to a topical treatment of systemic and localized pruritis, with particular interest as applied to psychogenic and senile pruritis.
Pruritis is a condition in which itching is the primary complaint and is unaccompanied by any visible causative lesion of the skin. Itching is perceived only in the skin, mucous membranes and cornea. The perception is localized to the dermoepidermal junction. No one receptor is uniquely adapted to itch perception.
There are many causes of localized or generalized pruritis. Many dermatoses have a predilection for certain areas of the body and can result in localized pruritis. Another cause of localized pruritis is notalgia paresthetica. Widespread itching or generalized pruritis is caused by a number of external factors and internal conditions. The most common group of causative factors are environmental provoking factors, including climate, particulate matter, detergents, insects, and infestations. The second most common group of causative factors includes a variety of skin diseases. The third most common group, yet most difficult to treat, includes psychogenic and senile pruritis. These last two are diagnoses of exclusion, yet they can be extremely debilitating and, since some cases are untreatable, can drive patients to suicide. Underlying systemic diseases account for 10% to 30% of generalized pruritis and are treated by reversing the underlying process.
When a patient begins scratching skin or mucous membranes that itch, no matter what the stimulation, a cycle to perpetuate the itch occurs. The cycle continues because of the cutaneous pleasure (orgasme cutane) one associates with scratching. Unless medical treatment interrupts this cycle, scratching continues until enough damage occurs that pleasure is replaced with pain.
Since no specific treatment is available and since no underlying etiology is elucidated in most patients, nonspecific palliative therapies are usually employed. These include emollients, counterirritants (menthol, phenol, camphor), anesthetics (pramoxine), or antiinflammatory agents (corticosteroids) applied topically. In addition to avoidance of irritants and systemic antipruritics, antihistamines or tranquilizers are usually added. For pruritis not associated with release of histamine, the nonsedating products are not beneficial. The majority of patients suffering from pruritis need systemic sedation to realize relief, which for obvious reasons adversely affects working people.